1. Technical Field
This invention relates generally to the field of electronic test equipment, and more particularly to a handheld electronic test probe assembly for testing miniature electronic circuit components, including passive, ceramic capacitors, resistors, inductors, and the like.
2. Description of Related Art
A typical tweezers is a handheld object used for any of various tasks for which it is designed, including plucking, holding, or manipulating an object. It includes two spring-biased legs having proximal ends that are joined together and opposing distal end portions that are spaced apart. A user grasps the tweezers in one hand and squeezes it in order to move the distal end portions of the legs toward each other so that they bear against an object of interest.
A “tweezers-type” electronic test probe is similar in that it is a handheld object having first and second legs that the user grasps and squeezes. As the user squeezes the legs, electrodes on the distal end portions of the legs come into contact with a device under test (i.e., a DUT). DUTs having parallelepiped shapes with dimensions as small as 0.020 inches by 0.010 inches by 0.010 inches, more or less, are frequently held and tested that way, with electrically conductive lines coupling electrical signals between the electrodes and a test instrument.
Although existing tweezers-type electronic test probes are convenient to use in some respects, they have some accompanying drawbacks. Consider, for example, a typical, commercially available, tweezers-type test probe. Mechanically, the legs are often not very stable. They can move sideways when squeezed together. As a result, the electrodes on the distal ends of the legs move sideways relative to the terminals on a DUT being held, and that movement can adversely affect electrical contact resistance and test results.
In addition, the electrodes of the existing tweezers-type electronic test probe take the form of two, opposing, electrically conductive elements having relatively flat, broad surfaces that bear against the terminals of the DUT. That arrangement results in uncertain contact resistance; it results in an uncertain effective serial resistance (ESR) that adversely affects test results.
Furthermore, an abbreviated Kelvin-type measurement arrangement on the existing tweezers-type electronic test probe disregards the ESR. Separate Kelvin-type sense and drive lines are provided for each electrode, but they do not achieve true Kelvin measurement because both sense and drive lines are connected to the same electrically conductive element so that they are connected together on the test instrument side of the ESR. As a result, drive current flowing through the ESR affects measurements made using the sense lines. Moreover, the entire existing tweezers-type electronic test probe fails to guard against stray serial impedance (SSI) and other stray impedances introduced by the top of a test bench, other nearby objects, and the user's hand gripping the tweezer legs. For these and other concerns that will become more apparent, a need exists for a better handheld electronic test probe assembly.